The goals of this project are: (1) To monitor AIDS patients enrolled in clinical trials of mono and combination therapies for HIV and CMV infections (e.g. combination drugs, drug + cytokines; drug + monoclonal antibodies). Our lab is responsible for the culturing of CMV from blood, urine and tissue specimens obtained from patients throughout the clinical protocol. (2) To isolate drug resistant variants of CMV from non-responding patients and subjec t them to viral and molecular analysis. This project is done in collaboration with the clinical center at NIAID, NIH. (3) Our laboratory participates in an NIAID/ACTG co-pathogen working group committee for the standardization of CMV viral burden assays. We are also acive in developing a new assay based on two color flowcytometry analysis of infected cells (with monoclonal antibodies to early vs. late antigens). This assay would provide a more rapid and more quentitative means to determine the susceptibility of CMV isolates to a given anti-viral drug. This project which is conducted on specimen and tissues derived from HIV/CMV infected patients is of prime importance for the evaluation of combination therapies in these patients. The data generated directly contribute to the efficacy evaluations of these therapies (Phase I/II trials).